A retiring Republican congressman said Thursday he is “heartbroken” over President Trump’s decision to withdraw troops from Syria, clearing the way for Turkey’s military to target Kurdish forces long allied with the United States, and ended his support for Trump’s reelection campaign as a result.

“Pull my name off the ‘I support Donald Trump’ list,’ ” Rep. John Shimkus (R-Ill.) said he told an aide Thursday in a KMOX radio interview. “We have just stabbed our allies in the back.”

Shimkus’s comments represent some of the starkest backlash Trump has received from his fellow Republicans. While prominent GOP foreign policy hawks such as Sen. Lindsey O. Graham (S.C.) and Rep. Liz Cheney (Wyo.) have been sharply critical of Trump’s decision to withdraw troops, none has gone as far as Shimkus in withdrawing support for Trump.

While Shimkus’s comments came amid the backdrop of a House impeachment investigation, spokesman Jordan Haverly said the remarks have “nothing to do with impeachment.”

In a statement provided by Haverly, Shimkus said that he is “angry and embarrassed” by Trump’s Syria decision.

“The Kurdish people are not a major global power, but they have been friends to the United States for decades,” he said. “. . . While my votes will continue to support the president’s domestic policy agenda, because of this terrible foreign policy decision, I asked that my name be removed from his campaign’s official list of supporters.”

Asked if Shimkus planned to vote for Trump’s reelection next year, Haverly did not immediately respond. Shimkus is retiring after his current term following what will be a 24-year House career.

Shimkus spoke to KMOX host Mark Reardon after publishing a commentary on Medium explaining why it is important for the United States to support Ukraine, regardless of its role in the ongoing impeachment probe.

In a July 25 phone call, as the United States withheld military assistance to the country, Trump asked Ukrainian President Volodymyr Zelensky to investigate allegations relating to the son of former vice president Joe Biden, as well as a discredited theory about Ukrainian involvement in the 2016 U.S. presidential election. The revelation that Trump asked a foreign leader to intervene against a domestic political rival sparked House Speaker Nancy Pelosi (D-Calif.) to endorse an impeachment inquiry last month.

Shimkus has opposed impeachment, posting on his Facebook page last week, “If Democrats want to remove President Trump from the White House, they should try to beat him at the ballot box.” In the interview Thursday, he said he was “troubled” by Trump’s behavior surrounding Ukraine but did not discuss impeachment.

One of 20 House members who serve as delegates to the NATO Parliamentary Assembly, Shimkus had much stronger words when it came to Trump’s decision to abandon the Kurds.

“It’s terrible. It’s despicable. I don’t have enough words to mention it,” he told Reardon. “I am embarrassed by it, and I am saddened for the Kurdish people.”

He added, “I think that your allies and friends, people that have been with you for years, you develop a relationship; and I’m a very loyal person, so loyalty is very important to me.”